In conventional display devices or other electronic devices, a transparent glass substrate is usually selected as a substrate material. However, the trend of display devices and other electronic devices is towards lighter weights and thinner shapes while electronic products usage and dependence increase with time. Therefore, a flexible display device (or another electronic device) having excellent properties such as mobility, flexibility, wearability, and impact resistance is needed. Although plastic substrates are selected as a flexible substrate collocated with an active display, an OLED illumination, and a printed circuit, they should meet the requirement of thermal resistance, light transmittance, dimensional stability, and the likes.
For example, a light diffusion film, a brightness enhancement film, and other optical films in a thinner display would be integrated into a single optical film. The integrated optical film must be closer to a heat source, and therefore being thermally deformed after long-time use (or during high temperature LCD processes). In addition, a display with a larger display area needs a higher brightness, leading to more heat being produced by a backlight module. Accordingly, enhancing the dimensional stability of the optical film is necessary in this field.